QMenu move in showEvent() create strange result on secondary screen

To compensate for a margin set in the style of the object, we are trying to move the QMenu object.
It produces a wrong result on the first opening of the QMenu on the secondary monitor (see Incorrect.png). Every other opening on any screen will be displayed correctly (see Correct.png)

Steps:

    - run the program

    - without opening the QMenu in the QToolBar of the QMainWindow, move the window to the secondary monitor of your computer.

    - try to open the QMenu

qtdiag tool results: